Sample Paper Grade 12 Ppt
-
Upload
vidit-kohli -
Category
Documents
-
view
21 -
download
0
description
Transcript of Sample Paper Grade 12 Ppt
![Page 1: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/1.jpg)
SAMPLE PAPER
Q1.Write the structure of 3-oxopentanal
![Page 2: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/2.jpg)
Ans. CH3 – CH2 - CO –CH2 – CHO
![Page 3: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/3.jpg)
Q2. What is the order of a reaction whose rate constant has the same units as those of rate of reaction?
![Page 4: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/4.jpg)
Ans. Zero
![Page 5: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/5.jpg)
Q3. Draw figure to show the splitting of d orbitals in an octahedral crystal field.
![Page 6: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/6.jpg)
![Page 7: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/7.jpg)
Q4. Why does nitrogen show catenation properties less than phosphorus?
![Page 8: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/8.jpg)
Ans. Due to more lone pair - lone pair repulsion, N-N is weaker than P-P.
![Page 9: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/9.jpg)
Q 5. Which Xe compound has distorted octahedral shape?
![Page 10: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/10.jpg)
Ans.
![Page 11: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/11.jpg)
Q6. Explain Frenkel defect in crystals.
•
![Page 12: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/12.jpg)
Ans.It occur due to the missing of ions from thenormal lattice site and occupies an interstitial site due to which electrical neutrality and stoichiometry are Maintained.
![Page 13: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/13.jpg)
Q7. Why is Bi (V) a stronger oxidant?
![Page 14: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/14.jpg)
Ans. On moving down the group, the stability of the +5 oxidation state decreases. This is due to the inert pair effect. Thus, Bi (V) is a stronger oxidant.
![Page 15: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/15.jpg)
Q8. Complete the following chemical equation P4(s) +NaOH (aq) +H2O(l) -----→
![Page 16: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/16.jpg)
Ans. P4 + 3NaOH + 3H2O → PH3 + 3 NaH2PO2
![Page 17: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/17.jpg)
Q9. Arrange the following in decreasing order of property indicated against each. Give reason .
• a) H2O, H2S, H2Se, H2Te (boiling point)
• b) NH3, PH3, AsH3, SbH3 (base strength)
![Page 18: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/18.jpg)
Ans.a)
b)
![Page 19: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/19.jpg)
Q10. Give chemical tests to distinguish between the following:
a) Methyl amine and Dimethyl amineb) Benzaldehyde and acetophenone
![Page 20: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/20.jpg)
a) Carbyl amine test or Hinsberg test .
b) Tollen’s test OR lodoform test.
![Page 21: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/21.jpg)
Q11.
a)Chloro acetic acid is more acidic than acetic acid. Give reason.
b)Aniline does not undergo Friedel-Crafts reaction. Give reason
![Page 22: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/22.jpg)
Ans.a) due to –I effect of Cl, it increases the stability
of carboxylate ion. b) Anhydrous act as Lewis acid and from salt
with aniline, in which aniline gets the positive charge and act as deactivating group.
![Page 23: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/23.jpg)
Q12. b) How would you account for the following:
a) Aldehydes are more reactive than ketones towards nucleophilic substitution reactions.
b)The boiling points of aldehydes and ketones are lower than that of the corresponding acids.
![Page 24: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/24.jpg)
Ans. a) explanation on the basis of inductive and
steric effect. b) type of attractive forces in acid H - bonding
type of attractive forces in aldehyde Dipole – Dipole interaction.
![Page 25: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/25.jpg)
Q13.Write two differences between molecularity andorder of a reaction.
![Page 26: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/26.jpg)
Ans. ORDER OF A REACTION• MOLECULARITY OF A REACTIONa)It is sum of the concentration terms on which the rate of reaction
actually depends or it is the sum of the exponents of the concentrations in the rate law equation.
• It is the number of atoms, ions or molecules that must collide with one another simultaneously so as to result into a chemical reaction.
b)It need not be a whole number i.e. it can be fractional as well as zero.• It is always a whole number.c)It can be determined experimentally only and cannot be calculated.• It can be calculated by simply adding the molecules of the slowest
step.
![Page 27: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/27.jpg)
Q14. Write the balanced chemical equation for the reaction of Cl2 with hot and conc. NaOH. Is this reaction a disproportionation reaction?
![Page 28: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/28.jpg)
Ans. 3Cl2 + 6NaOH → 5NaCl + NaClO3 + 3H2O Yes, chlorine from zero oxidation state is
changed to –1 and +5 oxidation states
![Page 29: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/29.jpg)
Q15. Compare the magnetic behaviour of [Ni(CN)4]2− and [NiCl4]2- on the basis of Crystal Field Theory. (Ni = 28)
![Page 30: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/30.jpg)
Ans. Ni(CN)4]2− is diamagnetic and [NiCl4]2- is paramagnetic.
![Page 31: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/31.jpg)
Q16.How would you account for the following?a)Hydrogen fluoride is much less volatile than
hydrogen chloride.b)Interhalogen compounds are very reactive.
![Page 32: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/32.jpg)
Ans. a) Fluorine is more electronegative than
chlorine. Therefore, HF undergoes stronger H-bonding than HCl. Hence, HF is much less volatile than HCl.
b) In interhalogen compounds, X−X bond is ′very weak and can be easily broken. As a result, interhalogen compounds are reactive.
![Page 33: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/33.jpg)
Q17.Complete the following chemical equationsa) Ca3P2(s) + H2O(l) →b)Cu2+(aq) + NH3(aq) → (excess)
![Page 34: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/34.jpg)
Ans a) 3Ca(OH)2 + 2PH3
b) {Cu(NH3)4}2+
![Page 35: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/35.jpg)
Q18. Calculate the efficiency of packing in case of a metal crystal for Face centered cubic.
![Page 36: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/36.jpg)
Ans. • In Face centered cubic (fcc):
As spheres are touching each other, evidently AC = r + 2r + r = 4rAC2 = AB2 + BC2 = a2 + a2 = 2 a2
• AC = / 2 a / 2 a = 4r• a = 4r = 2 /2 r• /2• a = 2 / 2 r• Volume of unit cell = a3 = (2 /2 r)3
• No of sphere in face centered cubic unit cell = 4• total volume of spheres = 4 x (4 π r3 / 3 ) • % efficiency = (volume of sphere/volume of unit cell) x 100• 4 x (4 π r 3 / 3)• % efficiency = ___________ x 100 = 74% (2 /2 r ) 3
![Page 37: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/37.jpg)
Q19. a) Write the formula of Tetraammineaquachloridocobalt (III) chloride.
b) Why is geometrical isomerism not possible in tetrahedral complexes having two different types of unidentate ligands coordinated with the central metal ion?
c) What is meant by the chelate effect? Give an example of chelate compound.
![Page 38: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/38.jpg)
Ans.i) ii) All bond position of the groups are same with
respect to each other . iii) Stability of coordination compound increases if a
bidentate or tridentate ligand is attached to central metal atom and form a 5 or 6 membered ring. This effect is called chelate effect. Ex.
![Page 39: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/39.jpg)
Q20. Account for the following:a)Bond dissociation energy of F2 is less than that
of Cl2 .b)SF4 is easily hydrolyzed whereas SF6 is not
easily hydrolysed.c)N2 is inert at room temperature.
![Page 40: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/40.jpg)
Ans. i) Due to small size of F, more into electronic repulsion b/w lone pairs of electrons.
ii) SF6 is sterically protected by 6 F atom. iii)Due to large bond dissociation energy of
NΞN.
![Page 41: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/41.jpg)
Q21. For the complex [Fe (en)2Cl2] Cl (a) Name the complex. (At. no Fe = 26). (b) What is the hybridisation and the shape of
the complex? (c) Predict the magnetic behavior of the
complex. (d) Draw the geometrical isomers.
![Page 42: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/42.jpg)
Ans. i)Dichloride-bis-(ethylenediamine)lron(III)
chloride . ii) Sp3d2 octahedral
iii) paramagnetic iv) geometrical structure
![Page 43: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/43.jpg)
Q22. How would you obtain the following?a)But -2-enal from ethanalb)Propanone from ethanalc)Benzoic acid from ethylbezene
![Page 44: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/44.jpg)
Ans.1) Ethanol → aldol condensation (reaction). 2) Ethanol with methyl magnesium halide
followed by hydrolysis. 3) Oxidation by KMnO4 / H+
![Page 45: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/45.jpg)
Q23.
![Page 46: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/46.jpg)
Ans.
![Page 47: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/47.jpg)
Q24. Why does PCl3 fume in moisture?b) With what neutral molecule is ClO-
isoelectronic ? Is that molecule a Lewis base? c) When HCl reacts with finely powdered iron, it
forms ferrous chloride and not ferric chloride. Why?
![Page 48: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/48.jpg)
Ans. a) In the presence of (H2O), PCl3 undergoes hydrolysis giving fumes of HCl .
PCl3 + 3H2O→H3PO3 + 3HClb) ClF. Yes,it is Lewis base due to presence of lone
pair of electronsc) Its reaction with iron produces H2. Fe + 2HCl→FeCl2 + H2 ; Liberation of hydrogen
prevents the formation of ferric chloride.
![Page 49: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/49.jpg)
Q25. Discuss the nature of bonding in [Co(C2O4)3]3- on the basis of valence bond theory.
![Page 50: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/50.jpg)
Ans. [Co(C2O4)3]3-
• Explanation• d2sp3, octahedral, diamagnetic
![Page 51: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/51.jpg)
Q26Give reasons:a)p-Nitro benzoic acid has a lower pKa value than benzoic
acid.b)Although amino group is ortho and para directing in
aromatic electrophilic substitution reaction, aniline on nitration gives a substantial amount of meta-nitroaniline..
c)Acetone is highly soluble in water but benzophenone is not.
.
![Page 52: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/52.jpg)
Ans.a) -NO2 group at para position increases the
positive charge on C-1 due to –I and -R effect making the fission of O-H bond easier.
b) Anilinium ion is meta directing.c) Acetone can make hydrogen bonds with
water but benzophenone cannot due to the steric hindrance of two phenyl groups.
![Page 53: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/53.jpg)
Q27.Indicate the steps in the preparation of KMnO4
from pyrolusite ore. Write the ionic equationsfor potassium dichromate reaction with H2S.
![Page 54: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/54.jpg)
![Page 55: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/55.jpg)
Q28.
i) Answer the following :a) What is the basicity of H3PO3 and why?b) Why does fluorine not play the role of a
central atom in interhalogen compound?c) Why do noble gases have very low boiling
points?
![Page 56: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/56.jpg)
ii) Discuss the chemistry involved in Brown ring test for nitrate ion. Give equations also.
![Page 57: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/57.jpg)
Ans.i) a) Basicity 2 due to presence a of 2 OH bond
b) F has smallsize and high electronegativityc) presence of dispersion forces.
ii)
![Page 58: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/58.jpg)
Q29.i)Give example of pseudo first order reactionii.) Express the relation between the half life period of a reactant and its initial concentration for a reaction of nth order.
![Page 59: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/59.jpg)
iii)
![Page 60: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/60.jpg)
Ans.
i)Hydrolysis of cane sugar to produce glucose and fructose
ii) t1/2 α 1/(R)n-1 where n is the order of reaction
![Page 61: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/61.jpg)
iii)
![Page 62: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/62.jpg)
Q30. i.) Explain the mechanism of the reaction of acetaldehyde with HCN.
ii.) Carboxylic acids do not show properties typical of carbonyl compounds. Why?
iii)Carboxylic acids have much higher acidity than phenols. Why?
![Page 63: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/63.jpg)
i)Ans. Mechanism:
Step 1 - Addition of nuclephile CN – to form tetrahedral intermediate, change in hybridization of carbonyl C from sp2 to sp3
Step 2 - Protonation of the intermediate
![Page 64: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/64.jpg)
![Page 65: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/65.jpg)
ii) Due to resonance the positive charge on the carbonyl carbon is less. 1
![Page 66: Sample Paper Grade 12 Ppt](https://reader033.fdocuments.us/reader033/viewer/2022042610/577cc0b71a28aba71190d837/html5/thumbnails/66.jpg)
• iii) The higher acidity of carboxylic acids as compared to phenols is due to the following reasons:
• (1) The conjugate base of carboxylic acid, a carboxylate ion, is stabilised by two equivalent resonance structures in which the negative charge is at the more electronegative oxygen atom. The conjugate base of phenol, a phenoxide ion, has non-equivalent resonance structures in which the negative charge is at the less electronegative carbon atom. Therefore, resonance in phenoxide ion is less stable than in carboxylate ion.
• (2) The negative charge is delocalised over two electronegative oxygen atoms in carboxylate ion whereas it is less effectively delocalised over one oxygen atom and less electronegative carbon atoms in phenoxide ion. Thus, the carboxylate ion is more stabilised than phenoxide ion, so carboxylic acids are more acidic than phenols.